2. Deep Seafloor Features Mapping the seafloor – Bathymetry- study and mapping of seafloor elevations – Techniques Early explorers measured depth with rope Echo sounder- determines depth by measuring the time required for sound to leave a ship, reflect off the bottom, and return

3. Mapping the seafloor – Techniques Multibeam sonar system- takes several sounding at a time; faster Satellites- measure very large scale sea floor features by determining changes in sea surface elevation

4. Deep seafloor features – Continental shelf- nearly flat borders on the edge of continents that slope toward ocean basins – Continental slope- steep slope extending to seafloor

5. continental rise- gentle slope formed at the base of the continental slope, formed by accumulated sediments

6. Deep seafloor features – Abyssal Plain- vast plain extending seaward from base of continental slope – Mid- ocean ridge- underwater mountain range, typically having a valley known as a rift running along its spine

7. Deep Seafloor features – Seamount- steep sided volcanoes rising abruptly, sometimes piercing the sea surface to become islands – Guyot- flat- topped seamounts – Trench- long, narrow depressions of the sea floor; deepest parts of the ocean